In most current computer-based patient care systems a central data processor is passively linked to physiologic data acquisition units originally intended as stand-alone devices. This approach does not take full advantage of the digital computer in such a system. The broad objective of the proposed study is the development (design, construction, testing) of an actively linked integrated physiological data acquisition and analysis system which can be adapted for use in critically ill care units and specialized laboratories. Integration within the system is achieved by design of all units for data acquisition, display, and pre-processing as true computer peripherals. The digital communication structure of the system provides a measure of data reliability, data accuracy, and detection/diagnosis of patient alarms and systems malfunctions which exceeds that of passively linked systems. The proposed system has five subsystems: (1) physiologic data acquisition unit, (2) communication display unit, (3) satellite data processor/controller, (4) central data processor, and (5) central data station. The satellite data processor/controller incorporates a microprocessor to which the data units (acquisition, display, communication, pre-processing) are interfaced as peripheral devices. Design of all transducer amplifiers (pressure, respiration, temperature, thermal dilution cardiac output) incorporates control logic, high-quality components, and circuits which eliminate operator controls, resulting in amplifier modules with long-term stable operation without human intervention. Analog signal pre-processing results in significant reduction of data input to the central processor, allowing use of a small unattended digital computer in the system. The software structure provides for data analysis of pre-processed or raw analog data, alarm indications, and entry and listing of patient information. It generates hard-copy output of patient data and information, and serves to maintain a continuous systems serveillance in terms of hardware and software performance checks and diagnosis of malfunction.